Did you already look thru this: http://www.aumha.org/win5/a/shtdwnxp.php
In XP try this:
Open a command prompt in admin mode and type sfc /scannow, let it run and if it finds some files not proper it should replace them, then restart your computer in safe mode, try to shut down, if it works start up normally and see if it corrects it. That is all I got....

I hadn't seen that one. Seems like when searching via google, mostly more modern web pages are displayed to the user, not these older more juicy pages.

I would try that, but I am at BSOD right now - Inaccessible boot device.

The problem occurs if, when Windows 2000 installs, you or the OS select Standard PC instead of ACPI PC. So I have a W2K and XP installation with all my software already setup, but I need to get it back to ACPI PC. To ensure that my motherboard supports ACPI, I pulled out a spare SCSI drive and ran a fresh installation of W2K SP2. After installation, I checked the Device Manager, and sure enough, "Advanced Configuration and Power Interface (ACPI) PC" are installed. At this point, I connected my original SCSI HDD back up and booted to W2K and tried to switch from "Standard PC" to "Advanced Configuration and Power Interface (ACPI) PC" and got a BSOD at reboot. So there must be more to this switchero than simply changing the Standard PC. What else should be changed to get the system from "Standard PC" to "Advanced Configuration and Power Interface (ACPI) PC"?

It's been a decade plus but IIRC you need to upgrade over your 2k install to switch the HAL. If you switched in device manager and the computer BSOD then you need to do an emergency repair and manually replace the files back.

I am able to fix the BSOD by copying the "Standard PC" HAL.dll back into C:\WINNT\System32. Puts me back to square 1.

I do recall reading one suggestion to "upgrade over your w2k installation", but I was under the impression that this would require the user to reinstall all service packs and post service pack updates, for which I believe there are over 200 in the case of W2K past SP4. Maybe there is another feature in the Win 2000 boot disk - repair process that just upgrades the HAL?

In looking at the fresh installation of W2K on the temp SCSI drive, I see that aside from "Advanced Configuration and Power Interface (ACPI) PC", it also installs under Device Manager - System devices: "ACPI Fixed Feature Button" and "Microsoft ACPI-Compliant System". "Microsoft ACPI-Compliant System" uses a resource on IRQ 9. I am guessing that switching from "Standard PC" to "Advanced Configuration and Power Interface (ACPI) PC" isn't working because "Microsoft ACPI-Compliant System" is missing. I searched through the Add New Hardware Wizard, but cannot locate this item for manual installation anywhere.

Does anybody know how to force install "ACPI Fixed Feature Button" and "Microsoft ACPI-Compliant System"?

The HAL is differant. You cannot easily change an OS installed on non-ACPI or in non ACPI mode to ACPI or Visa-versa. Tried it with my Vostro laptop after a BIOS update, got BSOD and could never fix running XP without a re-install (none of the fixes worked). Found out that XP and earlier DO NOT really like ACPI mode if the BIOS implimentation is different ACPI spec than the OS ACPI spec (Current newest is V6.3 as of 2019). Ended up disabling ACPI mode in BIOS and all ran just fine. You can try the online fixes: https://forums.anandtech.com/threads/win2k-ac … ocedure.483116/
Good luck !
added: oops sorry late post AND glad you got out of BSOD

Read that one. Not sure what "1. Start Windows 2000 Setup as an upgrade." means. Sounds like doing a fresh installation of W2K to me, unless there is some kind of repair mode from the W2K boot installation disc that will change all the necessary ACPI registry settings and associated files.

Doing a fresh install of W2K and XP are the last resort. Install the OSes are easy, but installing all the updates and period correct software will take days and it is incredibly boring. I have one other system that is in the same boat so finding a solution to this which does not involve reinstalling the operating system is preferred.

EDIT: There is a procedure detailed here that I intend to try: https://zedt.eu/tech/windows/switch-windows-x … hout-reinstall/ The procedure is for Windows XP, but with any luck it will also work for W2K.

feipoa wrote on 2020-05-31, 03:47:

I intend to try: https://zedt.eu/tech/windows/switch-windows-x … hout-reinstall/ ...

I tried this procedure in XP first and it yielded an unbootable operating system, so I guess I'll try the "repair install" method next, whatever that is exactly, I'll soon find out. I don't recall seeing a "repair install" option when booting from the W2K CD. I recall an option to "repair", but it puts all the original (old) Windows CD-ROM files back onto the HDD.

feipoa wrote on 2020-05-31, 08:54:

I tried this procedure in XP first and it yielded an unbootable operating system, so I guess I'll try the "repair install" method next

Did you notice what the site says about that?

If you actually CONTINUE with this and your system is NOT actually an ACPI system, it will become unbootable.

Trying other methods won't work either if the system has no ACPI support. Or maybe the version is unsupported. There were various revisions of ACPI and they are all incompatible with each other. Updating the BIOS may also update ACPI support.

Win98 does not need or use ACPI to power-off the system. No idea how it does it exactly, but it just works on any ATX system.

derSammler wrote on 2020-05-31, 09:11:

Did you notice what the site says about that? […]
Show full quote

feipoa wrote on 2020-05-31, 08:54:

I tried this procedure in XP first and it yielded an unbootable operating system, so I guess I'll try the "repair install" method next

Did you notice what the site says about that?

If you actually CONTINUE with this and your system is NOT actually an ACPI system, it will become unbootable.

Trying other methods won't work either if the system has no ACPI support.

Yes I noticed that. Perhaps you missed a sentence I wrote above. I noted the following:

feipoa wrote on 2020-05-31, 02:46:

To ensure that my motherboard supports ACPI, I pulled out a spare SCSI drive and ran a fresh installation of W2K SP2. After installation, I checked the Device Manager, and sure enough, "Advanced Configuration and Power Interface (ACPI) PC" is installed.

So I already know this motherboard supports ACPI. Perhaps W2K Sp4 or some post-SP4 updates made ACPI incompatible? Or perhaps there is more to adding ACPI to a system installed with "Standard PC". I suspect the later.

But for anyone waiting and hoping to figure out what I reveal about the Windows 2000 boot CD repair procedure, you might just need to test that out on your own because I found a workaround to achieve soft-shutdown. It is related to something I alluded to previously but hadn't tested yet. You can go to the add hardware wizard and force an installation of "NT Apm/Legacy Interface Node". This puts the APM tab into your Control Panel - Power Options. There is a check-box option under this tab to "Enable Advanced Power Management Support". This box is checked by default in XP once you install the NT Apm Node, but for W2K, I had to check the box. I can now soft-shutdown. w00t!!!

Some users prefer to use "Standard PC" hal as opposed to ACPI because as it doesn't use virtual IRQ's, which are all routed through IRQ 9. ACPI uses virtual IRQ's.

Something else that is interesting - Windows 98SE appears to have the ability to add ACPI after the fact. ACPI will auto install when you, for example, install a hard drive from an AT system into an ATX ACPI-capable system. It also adds the "ACPI Fixed Feature Button" on its own. This is why Win98SE was able to soft-shutdown after installing the cloned HDD, but not W2K/XP. I'd imagine that if Windows 98SE is able to add ACPI post-installation that there may still be a way to get W2K and XP to, but we don't know all the particular steps.

EDIT: Another interest bit. I have 3 other systems which I attempted this APM fix on and it didn't work. The boards were an ATX PPRO board, an ATX Tyan Super7 board, and lastly a ATX MediaGXm system. If the soft shutdown feature of the Microsoft APM feature doesn't give with your motherboard's BIOS, either the computer will just restart when it is supposed to shutdown, or it will BSOD with "IRQ not less or equal". The Tyan Super7 board I tried even has an "ACPI function enable" feature in the BIOS, so it may in fact benefit from figuring out how to get the ACPI hal properly installed on W2K and XP, but I'd first have to run a solo W2K installation to ensure it works with ACPI.

feipoa wrote on 2020-05-31, 09:32:

...

But for anyone waiting and hoping to figure out what I reveal about the Windows 2000 boot CD repair procedure, you might just need to test that out on your own because I found a workaround to achieve soft-shutdown. It is related to something I alluded to previously but hadn't tested yet. You can go to the add hardware wizard and force an installation of "NT Apm/Legacy Interface Node". This puts the APM tab into your Control Panel - Power Options. There is a check-box option under this tab to "Enable Advanced Power Management Support". This box is checked by default in XP once you install the NT Apm Node, but for W2K, I had to check the box. I can now soft-shutdown. w00t!!!

Some users prefer to use "Standard PC" hal as opposed to ACPI because as it doesn't use virtual IRQ's, which are all routed through IRQ 9. ACPI uses virtual IRQ's.

In my personal (albeit limited) experience, success with W2k doesn't imply success with WXP. I've had W2k work like a charm, and WXP refuse to use ACPI.

I had a post about this in my OR840 thread: basically if the board's BIOS has a pre-1999 date, or if Microsoft decided its a "bad BIOS", WXP will not support ACPI.
Outrigger: an ongoing adventure with the OR840
In the post I reinstalled WXP and was "successful", but the system acted up when I swapped around some video cards.

I'm following this thread to see what happens though!

I ran a W2K fresh install on my Tyan Super7 board which has the "ACPI Function" option in the BIOS and also has the ACPI shutdown feature for Windows 98se. After installation I looked in Device Manager and W2K setup gave it the "Standard PC" hal. So that board isn't a good candidate. So far the only board which actually has a functioning W2K ACPI hal is the Gateway 2000 Athlon slot A, but I'm reluctant to try the W2K boot disc "repair install" method to see if it works. The system is setup fine with the APM soft-shutdown and I don't want to goof it up.

Perhaps someone will chime in here with their experience with the "repair install" method. Did you have to reapply SP4 and post-SP4 hotfixes? What about program registry registrations? Did they get messed up?